Molybdenum-titanium alloys



Patented May 11, 1954 UNITED* STATES PATENT OFFICE MOLYBDENUM-TITANIUMALLOYS John L.. Ham, Dearborn, Frederick P. Bens and Alvin J. Herzig,Detroit, and George A. Timmons, Ferndale, 'Mich., assignors to ClimaxMolybdenum Company, New York, N. Y., a corporationof Delaware NoDrawing. Application October 6, 1951, Serial No. 250,204

13 Claims. 1

glass, die-casting dies for brass and other metals,-

etc. This application is a continuation-in-part of applicants copendingiapplicationlserial No. 218,521, filed March 30, 1951, now abandoned.

The principal object of the invention is to provide improved cast alloysof molybdenum which have high melting points and which are capable ofbeing worked at elevated temperatures.-

It is a further object, of the invention. to provide improvedmolybdenumebase. alloys as castings of substantial sizev which haveincreased strength and hardness at both .room and elevated temperaturesand which exhibit a pronounced tendency. to retain at elevatedtemperatures hardening induced by working at elevated temperatures.

A still further object of this invention is topro- Yide improved castmolydenum-base alloys which have a lower specific gravity than puremolybdenum and thus are particularly suitedfor such applications as gasturbine blades. 7 V

A further object is to, provide molybdenumbase alloys in which thecarbide phase is di'spersed by thegaddition. of the alloying element.

The terms feast? and -casting asused in this specification are intendedto designate the product resulting from the melting of metal and Isolidifying the same .in a mold, whether or not the metal has beensubjected to subsequent working or machining.v The term fcasting is alsoused to designate any process or,;method-which involves melting metaland solidifying the same in a mold.

In accordance with this invention, highly desirable cast alloys ofmolybdenum are obtained This invention is also con-' when titanium isemployed as the alloying element. Such alloys exhibit improved strengthand hardness at elevated temperatures as well as a marked tendency toretain at elevated tern-2 peratures,..hardness induced by working,

It has previously been established that the presence of minute amountsof oxygen in a cast ing of molybdenum or a molybdenum-base alloyseriously impairs or destroys the capacity of the casting to be worked.at elevated temperatures if the oxygen is segregated at the grainboundaries in the form of certain metallic oxides.- The detrimentaloxide is visible on microscopic examination of intergranularfracturesand is believed to consist largely of M002. However, the oxidesof certain other metals, if present, are also detrimental. In any event,when examined 1nicr'o-' scopically, castings which can be workedat-elevated temperatures have no similar visible oxide segregations atthe grainboundaries which are similar. to the manifestations of Mo Oa-Cast molybdenum'containing less than about '.001%

oxygen 'can be worked at elevated temperatures butit is verydifiicultin'the production of cast ingots of molybdenum and its alloysto reduce the oxygen contentof the metal to such a 10w value.

As set forth in the patent to Frederick P.-Bens et al.,'No.2,580,273,-the detrimental oxide segregation is not found in molybdenumcastings containing not more than .005% oxygen if small amounts ofcarbon are present. Such castings can be worked at elevatedtemperatures.

It is now found that the detrimental oxides may' also be eliminated byincorporating in the casting certain metals which have a strongeraflinity for oxygen than does molybdenum and form oxides which either donot segregate at the grain boundaries or, if segregated at theboundaries, provide greater intergranular cohesion than does the oxideof molybdenum. Alu-' minumand beryllium have been found to fulfill theserequirements, and forgeable castings of molybdenum and molybdenum-basealloys containing up to a maximum of .05% oxygen have been producedbyineorporating small quantities of aluminum or beryllium or both in thecasting.

Carbon may also be present, if desired, and-small quantities of carbonor aluminum are particularly beneficial in molybdenum-base alloyscontaining beryllium.

The effect of oxygen on the molybdenum' titanium alloy castings of thepresent invention is similar to its effect in other molybdenum-basealloy castings, and consequently it is necessary to eliminatesegregations' of molybdenum oxide at i the grain boundaries if thecasting is to be workedat elevated temperatures.

This is preferably done by incorporating carbon, aluminum or berylliumin th'e alloy, either -singly' 'or in com bination. This critical effect01 oxygen on the capacity of the alloy to be worked is peculiar to castalloys as distinguished from those produced by sintering metal powders.

If carbon is present in amounts between .01% and 04% and no aluminum orberyllium is present, the maximum oxygen content which can be toleratedin a casting that must be worked at elevated temperatures is about.005%. The minimum quantity of residual carbon should, preferably,increase within these limits as the residual oxygen content approaches005%. Larger amounts of carbon up to a maximum of about 25% may bepresent in casting, that must be worked at elevated temperatures, butthe resulting additional carbides increase the diinculty of working thecast alloy without imparting other advantages and, therefore, it ispreferred that the carbon not exceed about 07%.

If aluminum or beryllium is present in adequate quantities, the maximumoxygen content which can be tolerated in a casting that must be workedat elevated temperatures is about 05%. The quantity of aluminum orberyllium must be at least sufiicient to stoichiometrically react withthe oxygen present in the final alloy to form A1203 or BeO, and ispreferably thre times that quantity in the case of aluminum. Thus,aluminum in the range of 003% to 4% or beryllium in the range of 001% to03% may be present. In actual practice, aluminum is preferred toberyllium for this purpose and, if beryllium is used, it is preferred touse small quantities of aluminum or carbon with the beryllium. Whenaluminum is present within th ran es stated, residual carbon ispreferably omitted altogether or does not exceed 02%. However, castmolybdenum-titanium alloys containing aliuninum and as high as 06%carbon can be worked at elevated temperatures. When beryllium is used,it is preferred that the carbon not exceed 06%.

Excellent results are achieved in the working of molybdenum-titaniumcastings containing carbon in the range of .02% to .05% and oxygen lessthan 003%; or aluminum from 003% to 2% and oxygen less than 02%; orberyllium from 001% to .02% and oxygen less than 02%. Quantities ofaluminum and beryllium above the minimum required to react with theoxygen have other beneficial effects and hence aluminuni may be presentup to a maximum of about 2.5% or beryllium up to a maximum of about 25%.However, as set forth hereinafter, the amount of titanium present mustbe reduced below its maximum if the aluminum exceeds about or theberyllium exceeds about 03% and the alloy is to be worked at elevatedtemperatures.

Molybdenum-base alloys containing aluminum or beryllium and theherein-disclosed process of producing such alloys are more fullydisclosed and claimed in applicants copending applications, Serial No.250,202, on Molybdenum- Tungsten-Aluminum Alloys, and Serial No.150,201, on Cast Alloys and Method for Heat- Treating the Same, bothfiled concurrently herewith.

Alloying molybdenum with titanium increases the room temperaturehardness as well as the hardness and strength at elevated temperatures.Titanium also reduces the grain size of the cast alloy to a greaterextent than other known alloying elements when present in amounts of2.5% or more, the refining effect increasing with increasing titaniumcontent. Cast molybdenum-titanium alloys containing more than about 14%titanium by weight cannot be worked at elevated temperatures to abeneficial degree. However, alloys in which the titanium percentage isat or below 14% by weight can be worked at elevated temperatures.Particularly useful alloys result when the titanium content is between.25% and 8%, and this range is preferred. The addition of titanium hasbeen found to be effective in increasing the retention of work-hardnessat high temperatures, this effect increasing with increasing amounts oftitanium. Percentages below about 25% titanium were not found to beparticularly advantageous. Alloys of from 25% to 14% titanium inmolybdenum comprise solid solutions at room temperature and have meltingpoints above 3000 F.

A portion of the molybdenum may be replaced by tungsten as long as thetungsten does not exceed the molybdenum remaining in the final alloy,without destroying the ability of the alloy to be worked at elevatedtemperatures; such substitution also increases hot-hardness, but to alesser degree than titanium. However, as the tungsten percentage isincreased toward the maximum of about alloys capable of being worked atelevated temperatures are formed only if the titanium percentage isproportionately decreased toward the minimum of 25%. It is to beunderstood that this relationship between the tungsten and titaniumcontents relates only to the maximum allowable titanium which may bepresent for a given tungsten percentage without interfering with workingat elevated temperatures, and that alloys containing less titanium thansuch maximum fall within the scope of this invention. Actual- 1y, it ispreferred to use no tungsten or amounts less than 10%. It has also beenfound advantageous, in improving the ease of working, for the oxygencontent to decrease toward the practical minimum of about 001% as theamounts of titanium or tungsten increase. In accordance with thesegeneralizations, an alloy containing 14% titanium should preferably contain approximately 001% oxygen.

The useful eiiects of titanium in molybdenumbase alloy castings arerealized as long as, in a given alloy, molybdenum is present in anamount exceeding the amount of tungsten present, if any, and the totalof the molybdenum and tungsten contents constitutes at least of thealloy. Minor quantities of other elements may also be present. Thus,certain hereinafter-listed transition elements produce advantageousefiects when added to the molybdenum-titanium alloys of the presentinvention. However, to produce a cast alloy which can be worked atelevated temperatures to a beneficial degree, the amounts of tungsten,other transition elements, aluminum and beryllium must be limited; thepre ferred alloys contain at least molybdenum. Thus, even in pure binaryalloys of molybdenum, the following beneficial transition elementsshould not be present in amounts exceeding the following percentages ifthe alloy is to be worked at elevated temperatures.

Beryllium amounts in excess-of 03% and upto a maximum of about .25% andaluminum in amounts in excess'of 31% and up. to. a maximum of 2.5% havean effect on workability similar to that of the'above transitionelements. They all produce a proportionateincrease in hardness at 1600F.. astheir quantities increase toward the above maximums.- The maximumamounts given above for beryllium, aluminum and each of the transitionelements other than tungsten correspond roughly to those quantities ofeach element which, when'added alone to molybdenum, will produce ahardness at 1600 F. of 200 V. P. N. (Vickers Pyramid. Numeral) in anannealed casting. It has not been possible with normal workingtechniques to achieve a worthwhile percentage of recovery from theworking of metals and alloys having greater hardness,-

buta beneficial hot-working at temperatures substantially above 1600 F.may be performed on the alloys of the present invention provided thehardness at 1600 F. does not exceed about 200 V. P. N. in an annealedcasting. The effects of all of the above-mentioned metals, also titaniumand tungsten, on hot-hardness andadditive and, therefore, when two arepresent the maximum permissible amount of one should be proportionatelyreduced from its maximum given to the extent that the other approachesits maximum if the-alloy is to be capable of being worked to abeneficial degree. Still further reductions on the same basis must bemade if more than two are present, and in all cases less than thosemaximums. gives the best re-.

sults. From the standpoint of high strength and hardness at elevatedtemperatures in a molybdenum-titanium alloy that is well adapted.

to working at elevated temperatures, the preferred alloying transitionelements are columbium, zirconium, vanadium and tantalum.

Molybdenum-base alloys characterized primarily by the beneficial effectsof. tantalum,

zirconium, columium and vanadium, respectively,

are more fully disclosed and claimed in applicants copendingapplications filed concurrently herewith, as follows:

Serial No. 250,205, Molybdenum-Tantalum Alloys Serial No. 250,206,Molybdenum-Zirconium Alloys serial No. 250,207, Molybdenum-ColumbiumAlloys Serial No. 250,203, Molybdenum-Vanadium Alloys um in molybdenum,but that the alloys may also contain quantities of unspecified elements,such as the above-mentioned transition .ele-

ments, which do not. appreciably impair the..-

beneficial effects oftitanium;. or destroy the. capacity of the alloytobe worked at elevated. temperatures to a beneficial degree.

By way'of exampleythe .following' alloyszmayz.

6 be worked. at. elevated-temperatures and are useful in practice:

Example 1 Titanium 2.5% Carbon.- i 054% Oxygen less than 005% Molybdenumbalance Example- 2 Titanium 2.7% Aluminum .10% Oxygen less than .05%Molybdenum balance.

Example 3 Titanium 13%- Carbon 015%- Oxygen less than: 005% Molybdenumbalance 1 Example 4 Titanium 7% Carbon 015% Oxygen less than .0025%Tungsten." 5% Molybdenum. balance Example 5 Titanium 6% Carbon .02%Beryllium 015% Oxygen. 03% Molybdenumbalance The alloys of thisinvention may .be made by a variety of procedures, but cast alloyscontaining carbon are preferably made by the process which consists inthe steps of (1) mixing molybdenum, titanium, carbon and. any otherdesired. elements inthe form of powder, in the desired proportions; (2.)pressing the mixture into successive pellets to form a continuous rod;

(3) sintering. therod to impart sufiicient strength to the same torender it self-supporting; and (4) arc-melting the sintered rod. as aconsumable electrode in a vacuum. and collecting the metal directly intoa water-cooled copper mold.

The starting materials. used in. the process are commercially puremolybdenum, preferably containing not more: than about 05% oxygen, andcommercially available carbon and titanium powders as" well as powdersofany other elements used. Metals in the form of small chips or granulesmay comprise part of the charge. The starting materials are analyzed forcarbon and oxygen, and the carbon required to reactstoichiometri'ca'lly-with the oxygen to form carbonmon'oxide and-toprovide a residual carbon content of at least 01% but less than 25% isemployed".-

The powder charge is 'fed into an extrusion die positioned. beneath: theram of" a reciprocating press wherein successive pellets of the powdermaterial are pressed continuously on top of preceding pellets to. formacontinuous rod of pressed. metal. powders. Pelleting pressures ofapproximately 10,000 p.-s. i. to 20,000 p. s. i. have been used, 14,000.p. s. i. normally being adequate; The pressing is accomplished in avacuum-tight container.

Sufficient strength to make the pressed metal rod self-supporting isimparted by sintering the rod in vacuum at -a temperature ofapproximately'2400 F. to 2900'F. for approximately a quarter of a minuteto several minutesw Sintering may 7 be accomplished by any well-knownmethod of heating; electrical resistance heating is preferred.

The sintered rod is then used as a consumable electrode in a vacuum arcfurnace. Melting is started by striking an are between the rod and astarting electrode comprising a pile of chips of the same or similaralloy placed on a disc of molybdenum at the bottom of the casting mold.A water-cooled copper mold has been found suitable for receiving themolten molybednumtitanium alloy without contaminating the alloy withcopper. Molten alloy striking the watercooled copper mold quicklysolidifies, forming a protective coating on the surface of the mold.Thereafter, the liquid alloy becomes the lower electrode and the upper,consumable electrode is mechanically fed toward the lower, liquidelectrode to maintain continuous melting with the proper arc spacing.

For steps 2, 3 and 4, the pressure within the container should be as lowas possible and should not exceed a maximum of 500 microns, andpreferably should be below 100 microns. All three of these steps may becarried out in the same container.

If aluminum or beryllium or any other relatively volatile element isemployed in the alloy, the above-described process cannot be practicedunder the degree of vacuum set forth above and hence it is necessary toemploy an inert atmosphere of higher pressure in the melting chamber. Anargon or helium atmosphere at or slightly above atmospheric pressure hasbeen found suitable for this purpose. Except for the change from vacuumto an inert atmosphere at higher pressure, the process previouslydescribed may be used. The desired quantities of alumi num or berylliumare added to the mixture of metal powders which are sintered to producethe consumable electrode.

Inasmuch as extremely minute quantities of oxygen impair the capacity ofthe alloy casting to be worked, the starting materials should be as lowin oxygen as possible and it is necessary to avoid the introduction ofsignificant quantities 1 of oxygen as a contaminant in the inertatmosphere. The inert atmosphere may be purified by circulating itthrough a commercial drying tower before introduction into the castingcontainer. The gas may be recirculated or re-used after passing over abed of titanium metal maintained at approximately 1500 F., and a bed ofmagnesium metal maintained at approximately 1100 F. Because of therelatively high volatility of aluminum and beryllium at the arctemperature, the pressure of the inert atmosphere within the castingcontainer is preferably maintained at substantially atmospheric pressureor slightly above, for example, up to about 15.5 pounds per square inch.The casting container is first evacuated and then flushed with the inertgas; and, during operation, the insert gas is bled into the castingcontainer to maintain atmospheric pressure or slightly above.

If carbon is employed in addition to aluminum or beryllium, the partialpressure of carbon monoxide in the melting chamber should be maintainedbelow about 100 microns. In some cases, this may require a flow of thepurified inert gas through the chamber.

One suitable form of apparatus for use in form-- ing, sintering andmelting the powder rod is disclosed in the copending application ofEdgar K. Leavenworth, Serial No. 787,797, filed November 24, 1947, nowPatent No. 2,651,952 issued September 15, 1953.

A large number of tests of molybedenumtitanium alloys indicated thatsuch alloys possess an unexpected tendency to retain work-hardness atelevated temperatures. The testing procedure and results are typified bythe following data.

The alloy of Example 1 in the form of a bar 1 inches in diameter and 2%;inches long having a hardness of 207 V. P. N. in the annealed castingwas heated in the range of 2500 F. to 2600 F. and extruded in a diehaving a diameter of .85 inch. After extrusion the hardness was 283 V.P. N. The as-extruded bar was then annealed for 1 hour at 2200 F. andthe hardness decreased only to 271 V. P. N. After annealing 1 hour at2400" F., the hardness was 248 V. P. N. The beneficial characteristic oftitanium in retaining work-hardness at elevated temperatures is apparentwhen it is noted that, in the absence of tanium, molybdenum similarlytreated and having the same carbon content lost all of its work-hardnessin 1 hour at 2000 F.

Microscopic examination of a large number of cast molybdenum-titaniumalloys indicated that the addition of titanium effects a redistributionof the carbide phase and substantially eliminates carbide segregation atthe grain boundaries. As a result of the carbide redistribution, thealloys are more easily worked at elevated temperature and have improvedplasticity.

The fact that molybdenum-titanium alloys of the present inventioncombine reduced specific gravity with high strength and retention ofworkhardness at elevated temperatures makes them peculiarly advantageousfor use in gas turbine blades.

All of the proportions given herein are proportions by weight in thefinal alloy.

What is claimed is:

1. A cast alloy consisting of at least molybdenum and characterized byits capacity to be worked at elevated temperatures and its capacity toretain a significant amount of work hardness after one hour at 2200 ER,said alloy containing from .25% to 14% titanium, from .003% to .4%aluminum, from zero to .02% carbon, oxygen less than .02%, and thebalance con sisting essentially of molybdenum.

2. A cast alloy consisting of at least 85% molybdenum and characterizedby its capacity to be worked at elevated temperatures and its capacityto retain a significant amount of work hardness after one hour at 2200F., said alloy containing from 25% to 14% titanium; at least one elementfrom the group consisting of carbon from .01% to .25%, aluminum from.003% to 2.5% and beryllium from .00l% to 25%; metal from the groupconsisting of the transition elements, vanadium from zero to 7%,chromium from zero to 2%, iron from zero to 1.3%, cobalt from zero to .9nickel from zero to .4%, zirconium from zero to 2%, columbium from zeroto 10%, tantalum from zero to 9%, and tungsten from zero to 10%, thetotal amount of metal from said group of transition elements beingfurther limited to an amount within the range from none to the amountwhich will increase the hardness of the annealed casting to a value notexceeding 200 V. P. N. at 1600 F.; and the balance consistingessentially of molybdenum.

3. A cast alloy consisting of at least 85% molybdenum and characterizedby its capacity to be worked at elevated temperatures and its capacityto retain a significant amount of work hardness after one hour at 2200F., said alloy containing from 25% to 14% titanium; from .003% to 4%aluminum; from-zero to-;02% carabon; oxygen less than .02%-; metal fromthe the annealed casting'to a value not exceeding 200 V. P. N. at 1600F.; and-thebalance consisting essentially of molybdenum.

4. A cast alloy consisting of at least 85% mo lybdenum and characterizedby its capacity to be worked at elevated temperatures, said alloycontaining from 25% to 14% titanium; at least one element from the groupconsisting of carbon from .0l% to .25 aluminum from .003% to 2.5% andberyllium from .001% to 25%; metal from the group consisting of thetransition elements vanadium from zero to 7%, chromium from zero to 2%,iron from zero to 1.3%, cobalt from zero to .9 nickel from zero to 4%,zirconium from zero to 2%, columbium from zero to tantalum from zero to9%, and tungsten from zero to 10%, the total amount of metal from saidgroup of transition elements being further limited to an amount withinthe range from none to the amount which will increase the hardness ofthe annealed casting to a value not exceeding 200 V. P. N. at 1600 F.;and the balance consisting of molybdenum.

5. A cast alloy characterized by its capacity to be worked at elevatedtemperatures and its capacity to retain a significant amount of workhardness after one hour at 2200 F., said alloy casting comprising fromto 14% titanium, carbon from .0l% to 25%, oxygen not more than .005%,and the balance consisting essentially of molybdenum.

6. A cast alloy characterized by its capacity to be worked at elevatedtemperatures and its capacity to retain a significant amount of workhardness after one hour at 2200 F., said alloy casting comprising from25% to 14% titanium, oxygen not more than .05%, aluminum in an amount atleast sufficient to react with all of the oxygen present and not morethan 2.5%, the maximum amount of aluminum within the range stated beingreduced toward 4% as the amount of titanium approaches its upper limit,and the balance consisting essentially of molybdenum.

'7. A cast alloy characterized by its capacity to be Worked at elevatedtemperatures and its capacity to retain a significant amount of workhardness after one hour at 2200 F., said alloy casting comprising from25% to 14% titanium, oxygen not more than .05%, beryllium in an amountat least suflicient to react with all of the oxygen present and not morethan 25%, the maximum amount of beryllium within the range stated beingreduced toward .03% as the amount of titanium approaches its upperlimit, and the balance consisting essentially of molybdenum.

8. A cast alloy consisting of at least 85% molybdenum and characterizedby its capacity to be worked at elevated temperatures, said alloycasting containing from 25 to 14% titanium, carbon from .01% to 25%,oxygen not more than 005%, metal from the group consisting ofthetransition elements vanadium from zero to 7%, chromium from zero to 2%,iron from zero to 1.3%, cobalt from zero to .9%, nickel from zero to 4%,zirconium from zero to 2%,.columbium from zero to 10%, tantalum fromzero to 9%, and tungsten from zero to 10%, the total amount of metalfrom said group of transition elements being-further limited to anamount within the range from none to the amount which will increase thehardness of the annealed casting to a value not exceeding 200 V. P. N.at 1600 F., and the balance consisting of molybdenum.

9. A cast alloy consisting of at least molybdenum and characterized byits capacity to be :worked atelevated.temperatures, saidalloy-castingcomprisingfrom 25% to 14% titanium,,oxy-

gen not more than .05 aluminum in an amount at least sufiicient to reactwith all or the oxygen present and not more than 2.5%, the maximumamount of aluminum Within the range stated being reduced toward .04% asthe amount of titanium approaches its upper limit, metal from the groupconsisting of the transition elements vanadium from zero to 7%, chromiumfrom zero to 2%, iron from zero to 1.3%, cobalt from zero to .9%, nickelfrom zero to 4% zirconium from zero to 2%, columbium from zero to 10tantalum from zero to 9%, and tungsten from zero to 10%, the totalamount of metal from said group of transition elements being furtherlimited to an amount within the range from none to the amount which willincrease the hardness of the annealed casting to a value not exceeding200 V. P. N. at 1600 F., and the balance consisting of molybdenum.

10. A cast alloy consisting of at least 85% molybdenum and characterizedby its capacity to be worked at elevated temperatures, said alloycasting comprising from 25% to 14% titanium, oxygen not more than .05%,beryllium in an amount at least sufficient to react with all of theoxygen present and not more than 25%, the

maximum amount of beryllium within the range stated being reduced toward.03% as the amount of titanium approaches its upper limit, metal fromthe group consisting of the transition elements vanadium from zero to 7chromium from zero to 2%, iron from zero to 1.3%, cobalt from zero to.9%, nickel from zero to 4%, zirconium from zero to 2%, columbium fromzero to 10%, tantalum from zero to 9%, and tungsten from zero to 10%,the total amount of metal from said group of transition elements beingfurther limited to an amount within the range from none to the amountwhich will increase the hardness of the annealed casting to a value notexceeding 200 V. P. N. at 1600 F., and the balance consisting ofmolybdenum.

11. A cast, molybdenum-base alloy characterized by its capacity to beWorked at elevated temperatures, said alloy casting comprising from 25%to 14% titanium, carbon from .01% to .07%, oxygen not more than .003 andthe balance consisting of molybdenum.

12. A cast, molybdenum-base alloy characterized by its capacity to beworked at elevated temperatures, said alloy casting comprising from 25%to 14% titanium, aluminum from 003% to .4%, carbon not more than 116%,oxygen not more than .05%, the minimum amount of aluminum within therange stated being that required to combine with all of the oxygen inthe alloy to form aluminum oxide, and the balance consisting ofmolybdenum.

13. A cast, molybdenum-base alloy characterized by its capacity to beworked at elevated temperatures, said alloy casting comprising from 25%to 14% titanium, beryllium from .001% to .03%, carbon not more than.06%, oxygen not more than .05 the minimum amount of beryllium withinthe range stated being that required to combine with all of the oxygenin the alloy to form beryllium oxide, and the balance consisting ofmolybdenum.

References Cited in the file Of this patent UNITED STATES PATENTS NumberName Date 969,064 Kuzel Aug. 30, 1910 1,363,162 Myers et a1 Dec. 21,1930 12 Number Name Date 1,670,463 Marden May 22, 1938 2,144,250 Allenet a1. June 17, 1939 2,304,297 Anton Dec. 8, 1942 FOREIGN PATENTS NumberCountry Date 718,822 Germany Mar. 24, 1942 OTHER REFERENCES Parke etal.: Treatise in Transactions of American Institute of Mining andMetallurgical Engineers, vol. 171, 1947, pages 416-430.

Kessler et al., 1949. Preprint No. 33 of paper presented at the AmericanSociety for Metals Convention, Cleveland, Ohio, October 17-21, 1949.

1. A CAST ALLOY CONSISTING OF AT LEAST 85% MOLYBDENUM AND CHARACTERIZEDBY ITS CAPACITY TO BE WORKED AT ELEVATED TEMPERATURES AND ITS CAPACITYTO RETAIN A SIGNIFICANT AMOUNT OF WORK HARDNESS AFTER ONE HOUR AT 2200*F., SAID ALLOY CONTAINING FROM .25% TO 14% TITANIUM, FROM .003% TO .4%ALUMINUM, FROM ZERO TO .02% CARBON, OXYGEN LESS THAN .02%, AND THEBALANCE CONSISTING ESSENTIALLY OF MOLYBDENUM.